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Last updated: 11 November 2026
Updated 12 November 2026. These KCSE Physics Paper 2 questions and answers are original practice questions in the 232/2 format, covering refraction, thin lenses, capacitors, electromagnetic induction, mains electricity, the photoelectric effect and radioactivity, with every calculation worked step by step. Physics Paper 2 for 2026 is on Wednesday 18 November, 2.00 to 4.00 pm, according to the KNEC 2026 KCSE Examination Timetable. They are written and checked by our team; they are not KNEC papers or a KNEC marking scheme.
How Physics Paper 2 (232/2) Is Organised
Paper 2 is a 2-hour theory paper marked out of 80. Section A has short questions worth 25 marks and Section B has longer structured questions worth 55 marks. Every question in both sections is compulsory, so there is no choice to make: work steadily and do not leave a calculation blank. Paper 1 (232/1, on Monday 16 November afternoon) carries mechanics and heat; Paper 2 carries light, waves, electricity, magnetism and modern physics. The practical, 232/3, closes the KCSE timetable on Friday 20 November.
| Topic group | What is commonly asked |
|---|---|
| Light | Reflection at plane and curved mirrors, refraction, critical angle and total internal reflection, thin lenses, the lens formula |
| Waves | Wave properties, sound, interference, the electromagnetic spectrum and its uses |
| Electricity | Cells, current electricity, Ohm’s law, electrostatics and capacitors, heating effect, mains electricity and cost of power |
| Magnetism | Magnetic effect of a current, electromagnetic induction, Faraday’s and Lenz’s laws, transformers |
| Modern physics | Cathode rays, X-rays, the photoelectric effect, radioactivity and half-life, electronics (diodes and rectification) |
KCSE Physics Paper 2 Questions and Answers (Section A Style)
1. A ray of light passes from air into glass. The angle of incidence is 40° and the angle of refraction is 25°. Calculate the refractive index of the glass. (3 marks)
Worked answer: n = sin i ÷ sin r = sin 40° ÷ sin 25° = 0.6428 ÷ 0.4226 = 1.52. A refractive index has no unit.
2. The refractive index of a glass block is 1.5. Calculate its critical angle. (2 marks)
Worked answer: sin c = 1 ÷ n = 1 ÷ 1.5 = 0.6667, so c = 41.8°. Total internal reflection happens when light in the glass meets the surface at more than 41.8°.
3. A capacitor of 2 µF is connected in series with one of 3 µF across a 12 V supply. Find the combined capacitance and the charge stored. (3 marks)
Worked answer: In series, 1/C = 1/2 + 1/3 = 5/6, so C = 1.2 µF. Q = CV = 1.2 × 10⁻⁶ × 12 = 1.44 × 10⁻⁵ C (14.4 µC). Each capacitor in series holds the same charge, so the voltages are 14.4 ÷ 2 = 7.2 V and 14.4 ÷ 3 = 4.8 V, which add up to 12 V.
4. State Lenz’s law and give one way of increasing the current induced in a coil when a magnet is pushed into it. (2 marks)
Answer: The direction of the induced current is such that it opposes the change producing it. The current is larger if the magnet is moved faster, a stronger magnet is used, or the coil has more turns. Any one.
5. Explain how a single diode produces half-wave rectification. (2 marks)
Answer: The diode conducts only when it is forward biased, so current flows through the load during one half of each alternating cycle and is blocked during the other half. The output is direct current that flows in one direction only, in pulses.
Section B Practice With Worked Calculations
6. An object is placed 30 cm from a converging lens of focal length 20 cm. (a) Find the image distance. (b) Find the magnification. (c) Describe the image. (6 marks)
Worked answer: Using the real-is-positive convention, 1/f = 1/u + 1/v. (a) 1/v = 1/20 − 1/30 = 3/60 − 2/60 = 1/60, so v = 60 cm on the other side of the lens. (b) m = v ÷ u = 60 ÷ 30 = 2. (c) Real, inverted and twice the size of the object. Check it with a ray diagram drawn to scale: one ray parallel to the axis then through F, one ray straight through the optical centre.
7. A transformer steps 240 V mains down to 12 V. The primary coil has 1,200 turns. (a) How many turns are on the secondary? (b) The primary current is 0.5 A and the secondary current is 9 A. Calculate the efficiency. (c) Give two causes of energy loss in a transformer. (7 marks)
Worked answer: (a) Ns ÷ Np = Vs ÷ Vp, so Ns = 1,200 × 12 ÷ 240 = 60 turns. (b) Input power = 240 × 0.5 = 120 W; output power = 12 × 9 = 108 W; efficiency = 108 ÷ 120 × 100 = 90%. (c) Eddy currents in the core, reduced by laminating it; heating in the copper windings, reduced by using thick wire; hysteresis losses, reduced by a soft-iron core; flux leakage, reduced by winding one coil over the other.
8. A 3 kW water heater is used for 2 hours every day for 30 days. Electricity costs an assumed KSh 25 per unit. Find the cost. (3 marks)
Worked answer: Energy = power × time = 3 kW × 2 h × 30 = 180 kWh, and 1 kWh is one unit. Cost = 180 × 25 = KSh 4,500. The rate here is invented for practice; the exam gives you its own rate.
9. Light of frequency 7.5 × 10¹⁴ Hz falls on a metal whose work function is 2.0 eV. Take h = 6.63 × 10⁻³⁴ Js and 1 eV = 1.6 × 10⁻¹⁹ J. Find the maximum kinetic energy of the emitted electrons. (4 marks)
Worked answer: Photon energy E = hf = 6.63 × 10⁻³⁴ × 7.5 × 10¹⁴ = 4.97 × 10⁻¹⁹ J = 4.97 × 10⁻¹⁹ ÷ 1.6 × 10⁻¹⁹ = 3.11 eV. Maximum kinetic energy = E − work function = 3.11 − 2.0 = 1.11 eV, or about 1.78 × 10⁻¹⁹ J. KCSE papers round the electron charge to 1.6 × 10⁻¹⁹ C; the exact value, 1.602 × 10⁻¹⁹ C, is listed on the NIST elementary charge reference value. Always use the constants printed on your paper.
10. A radioactive sample has a mass of 96 g and a half-life of 5 days. How much of it remains undecayed after 20 days? (3 marks)
Worked answer: 20 days ÷ 5 days = 4 half-lives. 96 → 48 → 24 → 12 → 6 g. So 6 g remains. Show each halving step: the method marks are there even if you slip on the last number.
Common Mistakes That Cost Marks
Leaving out units, especially on the final answer. Using the diverging-lens sign wrongly: in the real-is-positive convention a diverging lens has a negative focal length and its image distance is negative (a virtual image). Forgetting that the cost of electricity uses kilowatts and hours, not watts and seconds. Drawing ray diagrams freehand when the question asks for a scale drawing. In Section A, writing a long paragraph when 1 mark asks for one clear fact.
Next Steps for Physics Paper 2
Read the KCSE Physics Paper 2 revision guide, try the timed Physics Paper 2 challenge and the Physics Paper 2 likely topics page. Mechanics and heat are on the KCSE Physics Paper 1 (232/1) questions and answers page and the practical on Physics Paper 3 (232/3). The full week is in our KCSE 2026 timetable paper-by-paper guide, and every subject is on the KCSE hub.
Frequently Asked Questions
How many marks is KCSE Physics Paper 2?
80 marks in 2 hours: 25 in Section A and 55 in Section B. All questions are compulsory.
What topics are in Physics Paper 2?
Light and lenses, waves and the electromagnetic spectrum, electrostatics and current electricity, magnetism and electromagnetic induction, mains electricity, and modern physics such as the photoelectric effect, X-rays and radioactivity.
When is Physics Paper 2 in 2026?
Wednesday 18 November 2026, 2.00 pm to 4.00 pm, the afternoon of Geography Paper 2.
Do you have the KCSE Physics Paper 2 marking scheme?
No. These are original questions with worked answers that follow the marking style, not KNEC material.
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